Bug 58431 - Custom Converter is not triggered when value is changed at runtime with binding mode as "OneWay"
Summary: Custom Converter is not triggered when value is changed at runtime with bindi...
Alias: None
Product: Forms
Classification: Xamarin
Component: Forms ()
Version: 2.3.4
Hardware: PC Windows
: --- normal
Target Milestone: ---
Assignee: Bugzilla
Depends on:
Reported: 2017-07-27 12:00 UTC by Muthu kumaran.G
Modified: 2017-07-29 21:53 UTC (History)
6 users (show)

Is this bug a regression?: ---
Last known good build:

Binding issue (285.65 KB, application/x-zip-compressed)
2017-07-27 12:00 UTC, Muthu kumaran.G

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Description Muthu kumaran.G 2017-07-27 12:00:37 UTC
Created attachment 23844 [details]
Binding issue

Hi Team,

We have bind a string property in the data model to Label's Text property with binding mode as "OneWay" and used the converter to customize the text value. While initialization of label, the converter gets triggered and the label's text gets changed as expected. But if we changed the text at runtime for example, in a button click event, the text gets changed but the converter is not triggered.

Additionally, if the binding mode is "TwoWay" the converter gets triggered and text value changed as expected.

we have tested in latest stable Xamarin.Forms version (v

I have attached the sample in which the issue gets replicated as reported. Could you please check with the above sample and look into the issue and please update the further details asap.

Muthu G
Comment 1 Paul DiPietro [MSFT] 2017-07-29 21:53:14 UTC
You are changing the label's text value and not the value of the text which it is bound to. It works when you use TwoWay because the label's text is updating its bound value on the ViewModel (when you define <local:DataModel x:Name="ViewModel"/> in your XAML), which is in turn triggering the converter to update the label's text. Assigning ViewModel.Data to "Data 2" in your code instead of the label.Text value will enable the behavior to work as you expect.